There’s a lot of talk about developing Australia’s north, of doubling the agricultural output of this region and pouring billions of dollars into new infrastructure such as irrigation. But what about the natural values of this region and it’s potential for carbon storage today and into the future? Can we develop the north and still retain these other values?

In our latest paper we´ve found that agricultural development could have profound impacts on biodiversity OR a relatively light impact, it all depends on how and where it’s done. If managers and decision makers want our sweeping northern savannas to serve multiple purposes then they need to plan strategically for them.

Changes in woody vegetation from European settlement (end of 18th century). Whereas only 1/3 of the original woody vegetation cover remains in the south east of Australia the Tropical savannas of northern Australia currently occupy 99% of their original extent. The black outline delimits (roughly) the study area. Source: ABARES (Australian Bureau of Agricultural and Resource Economics and Sciences, Australian Government).

The northern savannas occupy a vast area, approximately the combined size of both France and Germany! This region possesses a relatively intact cover of native vegetation largely consisting of open eucalypt woodlands with a grass understorey. Extensive pastoral activity has modified the composition and structure of northern savanna forests and woodlands, but the biodiversity of these ecosystems remains relatively intact and hugely important due to its high degree of endemism and uniqueness. These lands also hold considerable potential for the storage of carbon by managing the manner in which fires are allowed (savanna burning management is of increasing interest in the context of greenhouse abatement because of its potential of altering the rates of carbon sequestred in soil and vegetation; it also has the potential to provide culturally appropriate livelihood opportunities for remote Aboriginal communities).

But there are many calls to develop Australia’s north. Based on soil properties, a fifth of this region is also deemed highly suitable for agricultural intensification. In this study we analysed the trade-offs between biodiversity, carbon, and agricultural intensification in northern Australia. We compared maps of agricultural intensification potential (soils potential to support irrigated annuals, irrigated perennial and irrigated improved pastures) with the geographic distributions for 611 native species and 43 vegetation communities to see how they overlap. We also compared the distribution of areas with larger carbon storage potential that are suitable for carbon farming.

We explored five alternative scenarios that looked at different approaches to development and how these could impact the unique biodiversity values of this region. One evaluated what might happen if only agriculture was considered in planning for agricultural expansion; another if biodiversity conservation was the only consideration; the third was if only carbon-farming was considered; the fourth was if farming, biodiversity and carbon were all given equal weighting, seeking to balance the three goals; and the final scenario looked at saving as much biodiversity as possible while still allowing for carbon farming and significant agricultural development.

Areas of potential conflict (trade-offs) or synergies between the three land-uses evaluated in this study (agricultural development, carbon farming and biodiversity) as well as their implications for policy making

We found that if all suitable soils were converted to agriculture, that habitat of three species would disappear, and 40 species and vegetation communities could lose more than 50% of their current distributions.

But agricultural development doesn’t have to have this impact. Their analysis showed that it’s possible to zone this region such that agricultural development could still occur on over 56,000 km2 with a significantly lower impact on biodiversity values and carbon farming. Our analysis suggests there is a significant opportunity to dramatically increase the protection of biodiversity with a minor expansion of the reserve system in northern Australia. By expanding the protected area network to capture an additional 5% of northern Australia, we could dramatically increase the representation of the biodiversity features from 29% to 57% (proportion of current suitable areas for species that would be protected) .

Our study quantifies (number of ha) and maps the areas of potential conflict and synergies between irrigated agriculture, biodiversity values and carbon farming. The methodology we used ranks the landscape The yellow and green areas indicate zones of overlap between areas of high conservation value (areas ranked in the top 5, 10 and 30% of the landscape ranking on the basis of the distributions of 654 biodiversity features) and areas highly suitable for irrigated agriculture (this is, areas of potential conflict between agricultural development and biodiversity conservation). The map also shows the sites where these areas of potential conflict between biodiversity and agriculture overlap with areas highly suitable for carbon storage (carbon farming schemes). Carbon farming Panels I, II, III and IV show these overlaps in detail for four different areas of the study area.

The development of extensive areas of irrigated agriculture might also cause potentially negative impacts on other industries such as tourism. Our approach could be built on to help evaluate trade-offs during planning and decision-making in relation to agricultural development in northern Australia, that incorporates more attributes than we have included in our study. For example, many other cultural, historical, social and economic can be mapped to provide an early indication of likely conflicts and trade-offs. The advantage of our approach is that it helps identify development footprints that have the lowest possible impact on biodiversity, while still providing strong economic opportunity. It can also help to identify where in the landscape are places that should most urgently be protected to avoid the worst outcomes of development for biodiversity.

The work has application beyond northern Australia. The analysis provides a template for policy-makers and planners to identify areas of conflict between competing land-uses, places to protect in advance of impacts, and planning options that balance the needs of agricultural and conservation.

Australia’s northern savannas are one of the few remaining large and mostly intact natural areas on the planet. Their biodiversity and ecosystem values could be threatened if proposed agricultural development proceeds. Some trade-offs will be necessary if those values are to be retained in the landscape – both for us today and for generations to come.